If your friend’s rabbit is an adult male ( or at least 5 months old) they should be able to see testicles. They look like pink kidney beans. Rabbits can sometimes hide them, but if he is relaxed, and old enough, they should be visible.
Is Hope spayed? Besides the obvious health benefits to that, she would be far less territorial about a new rabbit coming into her home and her room, if she is spayed. And if she isn’t spayed, and the friend’s rabbit is a male, accidents can happen. All it takes is a few seconds for rabbits to get together, if a cage wasn’t closed properly. And rabbits have been known to mate through cage bars, so you should never have an unspayed rabbits housed directly next to an unneutered male.
If Hope is spayed, it would probably be okay to house the rabbits in the same room, but you will have to have this new bunny spayed or neutered before you can think about bonding Hope with him or her. It is usually a lot easier to bond a spayed female with a neutered male, but you can bond same gender rabbits too.